Low-cement aluminum-magnesium Spinel Refractory Castable is an important material for ladle lining. It is mainly made of corundum, special grade alumina clinker, fused magnesia or high purity magnesia and magnesium-aluminum spinel, and is prepared using low cement technology. It is also called corundum or high aluminum-magnesium spinel refractory castable, also called composite aluminum-magnesium spinel refractory castable. Due to its excellent performance, it has been used in large and medium-sized ladles, and its service life can reach 100~270 times.
Raw material composition of low-cement aluminum-magnesium spinel refractory castable
The composition materials of low-cement aluminum-magnesium spinel refractory castable generally choose high-purity or synthetic refractory raw materials. Aluminate cement CA-70 or CA-80 is used as a binder. α-Al2O3 and SIO2 ultrafine powder and admixtures are added. According to the mix ratio requirements of the castable, various materials are accurately weighed and 4.5%~5.8% of crystal water is added. Mechanical stirring and vibration molding, drying after natural curing, and finally the physical and chemical properties of the material are tested. Fused white corundum is used as refractory aggregate and powder; fused magnesia sand powder, high-purity magnesium aluminum spinel powder box α-Al2O3 ultrafine powder are all added to the refractory powder. In another group of experimental materials, a small amount of SIO2 ultrafine powder is also added. Aluminate cement CA-70 is used as a binder, and its dosage is 3%~5%. Polyphosphate is used as a water reducer, and its dosage is 0.14%~0.22%. When aluminate cement solidifies too quickly and construction is difficult to ensure, citric acid and other retarders should be added. The critical particle size of refractory aggregate depends on the thickness of the ladle lining working layer. The mass ratio of refractory aggregate to refractory powder is about 7:3. The dosage of quick-drying agent is suitable when the sample is suddenly placed in a 550℃ circuit and kept warm for a certain period of time before being taken out and the sample does not burst.
Corundum-spinel low-cement castable is made of corundum as the main raw material, with an appropriate amount of spinel fine particles and micro powder (15~30wt%) added. A small amount of cement (3~5wt%) is added to make the castable. In the 1990s, another type of corundum-spinel castable was developed. Unlike synthetic spinel, this type of castable contains magnesia fine powder in the matrix part, which can react with alumina fine powder at high temperature to form in-situ spinel.
In-situ spinel castables have great advantages in certain application areas, such as ladle wall and ladle bottom castables. Due to its better slag resistance, it has become the main technical route in the past 20 years.
Presynthetic spinel corundum castables are widely used in other products such as prefabricated parts such as air-permeable bricks, seat bricks, and nozzles. The performance characteristics and applications of corundum/spinel castables and corundum/magnesia in-situ spinel castables have been discussed in many research reports.
Spinel is added to corundum castables for two purposes: first, to improve slag resistance and second, to improve thermomechanical properties. Under harsh slag erosion conditions, spinel-containing refractories show better performance. The samples with spinel addition showed significantly reduced slag penetration and slag erosion at the metal/slag interface.
Aluminum-magnesium spinel ladle castable of unshaped refractory materials
Aluminum-magnesium spinel castable is mainly made of corundum, special-grade bauxite clinker, electric melting or high-purity magnesia sand and aluminum-magnesium spinel, and is configured with low cement technology. This material is also called corundum or high-aluminum-magnesium sand spinel refractory castable, also called composite aluminum-magnesium spinel refractory castable. Because it is mostly used in various ladles, it can also be called ladle castable.
The characteristics of aluminum-magnesium spinel refractory castable are: high temperature resistance, strong resistance to structural spalling, resistance to chemical erosion of steel slag, resistance to rapid cooling and heating, non-sticking to molten steel, and erosion resistance. The pouring vibration method is used for construction.
The constituent materials of aluminum-magnesium spinel refractory castables generally select special-grade refractory raw materials, which are scientifically matched. The critical particle size of refractory aggregate depends on the thickness of the ladle working lining. High-purity CA70 aluminate cement is used as a binder. When the aluminate cement solidifies too quickly and it is difficult to ensure construction, citric acid and other retarders should be added. The matrix is composed of corundum powder, spinel powder, magnesia powder, α-Al2O3 powder and SiO2 ultrafine powder. When the refractory aggregate material and particle composition are matched, these refractory powders (including ultrafine powders) are used for rigorous and scientific formula design to make high-tech aluminum-magnesium spinel refractory castables with good slag penetration inhibition and slag erosion resistance, and obtain good use effects.
Practice in recent years has proved that composite aluminum-magnesium spinel refractory castables with excellent performance should be optimized, developed and used in close combination with the use conditions of ladles and thermal equipment to achieve good use effects and significant economic benefits. To purchase high-quality aluminum-magnesium spinel castables, please contact Rongsheng Manufacturer for free samples and quotations.
